Non-retrun valve

Abstract

 A valve (10) having a port (25) defined by a plurality of lips (30,31) each lip comprising elongate inner and outer portions (30a,31a,30b,31b) linked by an elongate sealing portion, wherein a lip is resiliently deformable from a first position in which the port (25) is closed by engagement of the sealing portions with one another to a second position in which the port is open, the valve being characterised in that the inner portion (30a,31a) of the deformable lip is bowed in inwardly along its long axis.

Description

[0001] The present invention relates to a valve, and more particularly, to a valve including resiliently deformable lips which can be deformed from a closed position to an open position and then can resume the closed position. Valves of this sort are sometimes called 'cuspic' valves.

[0002] Prior art cuspic valves are found in use in the sludge processing industry as one-way or non-return valves on the inlets and outlets of sludge pumps. A prior art cuspic valve on the inlet of a positive displacement pump works as follows. During the upstroke of the positive displacement pump when fluid is being drawn into the pump, the fluid pressure at the inlet deforms the lips of the valve such that they pucker open, thereby permitting fluid into the pump. During the downstroke of the positive displacement pump when fluid is expelled from the pump, the lips resume their closed position sealing off the pump inlet.

[0003] Over a period of time, it has been found that the lips of such valves tend to petal out or yawn open such that the lips can no longer form an effective seal against one another. This is thought to be a reaction to mechanical fatigue and/or chemical attack from the sludge. As a result, the efficiency of the associated pump can be severely impaired.

[0004] The present invention is based on the discovery that the shape of the lips can be selected to increase the inherent structural resistance to the above-mentioned distortion.

[0005] Known moulded cuspic valves are formed with the shape of the valve lips defined in one of two ways: either they are finished across the lip length with a uniform thickness and are square; or they have a convexed shape (where the lips are bowed outwards) in an attempt to support the pressure more evenly across the surface of the moulding.

[0006] The present invention provides a valve having a port defined by a plurality of lips, each lip comprising elongate inner and outer portions linked by an elongate sealing portion, wherein a lip is resiliently deformable from a first position in which the port is closed by engagement of the sealing portions with one another to a second position in which the port is open, the valve being characterised in that the inner portion of the deformable lip is bowed inwardly along its long axis.

[0007] The bowing of the deformable lip, especially at its inner portion, increases the inherent structural resistance of valve to the above-mentioned distortion.

[0008] The internal lip profile determines where the valve seals and it is here that a valve will fail if there is any distortion in the material. The inward bowing of the lips helps to seal effectively by pressing each lip against each other as the outer part of the valve tries to splay apart.

[0009] The outer portion of the deformable lip can also be bowed inwardly along its long axis. Preferably, all of the lips are deformable.

[0010] In one embodiment, the valve comprises a single pair of lips.

[0011] In another embodiment, the valve comprises three pairs of lips. Each pair of lips extends outwardly from a single, central region.

[0012] In another embodiment, the valve comprises four pair of lips. Each pair of lips extends outwardly from a single, central region, the lips thereby forming a cross shape in the first undeformed position.

[0013] The scope of the present invention is not limited by the material from which the valve is made nor its method of formation. For example, the valve can be made from rubber or plastics and can be manufactured by moulding or shaped on a former.

[0014] The degree of bowing of the outer portion can be different to that of the inner portion.

[0015] Preferably the bowing of the inner portion is greater than the bowing of the outer portion.

[0016] Exemplary embodiments of the invention are hereinafter described with reference to the accompanying drawings, in which:

Figures 1(a) and (b) show perspective views of a single lip-pair non-return valve in accordance with the present invention;

Figure 1(c) shows the valve of Figures 1(a), 1(b) when viewed in cross-section from the line A-A in Figure 1(b);

Figure 2(a) shows a perspective view of another single lip-pair non-return valve in accordance with the present invention;

Figure 2(b) shows the valve of Figure 2(a) when viewed in cross-section from the line B-B in Figure 2(a);

Figure 2(c) shows the valve of Figure 2(a) when viewed from above with parts removed;

Figure 3(a) shows a perspective view of a three lip-pair non-return valve in accordance with the present invention;

Figure 3(b) shows a cross-sectional view from the line C-C in Figure 3(a) of the valve in Figure 3(a);

Figure 4(a) shows a perspective view of a four lip-pair non-return valve in accordance with the present invention; and

Figure 4(b) shows a cross-sectional view from the line D-D in Figure 4(a) of the valve in Figure 4(a).

[0017] Referring to Figures 1 (a-c), a single lip-pair cuspic valve, made from a resiliently deformable material such as natural or synthetic rubber, is generally designated 10. The valve 10 comprises an annular base 12 at a first, inlet end thereof; a port 25 at a second opposite outlet end thereof; and a wall 14 connecting the base 12 and the port 25 to each other and defining a chamber therebetween.

[0018] The port 25 is defined by a pair of lips 30,31 each lip comprising elongate inner and outer portions suffixed a and b, respectively, and an elongate sealing portion suffixed c which as illustrated in Figures I (a) and 1(b) engages the sealing portion on the other lip. The valve 10 is deformable such that the lips 30,31 pucker open such that their sealing portions 30c,31c do not engage each other, thus forming an outlet. Once the deforming force is removed, the lips 30,31 resume the illustrated closed position.

[0019] This may be further illustrated by considering the operation of the valve 10 in use on the inlet of a positive displacement pump. The valve 10 is arranged such that the lips 30,31 are closer to the internal chamber of the displacement pump than is the base 12. During the upstroke of the pump when fluid is being drawn in to the pump, the fluid pressure entering the valve 10, as illustrated by the arrow F in Figure 1(a), causes the deformation and hence the puckering open of the lips 30,31 to permit fluid flow through the valve 10. During the downstroke of the pump, the lips 30,31 resume their closed position (where the sealing portions 30c,31c seal against each other) thereby closing off the pump inlet.

[0020] In accordance with the present invention, the inward bowing of the lips 30,31 increases the inherent structural resistance of the valve 10 to the aforementioned distortion. This is thought to be the case because as the valve starts to distort by yawning open, as is believed to be inevitable, the shape of the lips 30,31 forces the sealing portions 30c, 3 1 c closer together at least in the region of their inner portions 30a,31a, thereby maintaining the seal.

[0021] The remaining Figures show the concept of the present invention applied to other types of cuspic valve. Throughout these Figures an analogous system of reference numerals has been used.

[0022] The internal lip profile of the cuspic valve according to the invention provides great improvement in the overall valve reliability since this is the area where the valve seals and thus it is here that the valve will fail if there is any distortion in the rubber or other material from which the valve is made. As there is usually some degree of distortion to rubber or plastics material after being submerged in a chemical solution of some kind, there will nearly always be some degree of splaying out of the valve lips. It is here that having a concave shape to the internal side of the lips of the cuspic valve according to the invention help to seal by pressing against each other as the outer part of the valve tries to splay apart. This helps to improve the life of the cuspic valve, whether it is moulded or formed, or made from a natural or synthetic material. Since a cuspic valve splays away from the centre as the material swells, the inner bow helps to continue the seal area and thereby extend the life of the valve. Regardless of the outer valve shape on the cuspic valve, the inner profile according to the invention will extend the life of the valve, even when the valve distorts, because it accommodates the natural distortion that has to be accepted within the interaction between a chemical solution and a moulded or formed cuspic valve.

Claims

1. A valve having a port defined by a plurality of lips, each lip comprising elongate inner and outer portions linked by an elongate sealing portion wherein a lip is resiliently deformable from a first portion in which the port is closed by engagement of the sealing portions with one another to a second position in which the port is open, the valve being characterised in that the inner portion of the deformable lip is bowed inwardly along its long axis.

2. A valve as in Claim 1, characterised in that the outer portion of the deformable lip is also bowed inwardly along its long axis.

3. A valve as in Claim 1, characterised in that the degree of bowing of the outer portion is different to the degree of bowing of the inner portion.

4. A valve as in Claim 3, characterised in that the degree of bowing of the inner portion is greater than the degree of bowing of the outer portion.

5. A valve as in any one of the preceding claims, characterised in that all of the lips are deformable.

Drawing